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Fix EliminateLimit not eliminating limits under LogicalPlan::Extension nodes. (#25577) - #436
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…sion` nodes. (apache#25577) ## Which issue does this PR close? <!-- We generally require a GitHub issue to be filed for all bug fixes and enhancements and this helps us generate change logs for our releases. You can link an issue to this PR using the GitHub syntax. For example `Closes #123` indicates that this PR will close issue #123. --> - Closes #. ## Rationale for this change apache#22298 updated the logical plan optimizer to apply optimization rules in place to avoid `Arc` unwrap/rewraps with a new `map_children_mut()` function. This function unconditionally updates the children of all logical plan nodes except for `LogicalPlan::Extension` nodes. For `Extension` nodes, it only updates the children if the mapping function returns `true` for any of the children, signifying that a child was updated. When the `EliminateLimit` rule prunes a limit that has 0 skip and fetch, it modifies the node but does not return that it modified anything. This is fine for every case except for if the limit is underneath a `LogicalPlan::Extension` node, since it that case we ignore the output from the rule. ## What changes are included in this PR? This change adds a failing test, a fix to `EliminateLimit`, and changes `map_children_mut()` to unconditionally update the children of `LogicalPlan::Extension` nodes. The change to `map_children_mut()` could be left out, but I wouldn't be surprised if there are other optimization rules that modify the node without returning `transformed=true`, so this is done to avoid finding and fixing all of those cases. <!-- There is no need to duplicate the description in the issue here, but it is sometimes worth providing a summary of the individual changes in this PR. --> ## What is the testing strategy for this PR? I added a test that replicates the issue and fails without my fixes. <!-- We typically require tests for all PRs in order to: 1. Prevent the code from being accidentally broken by subsequent changes 2. Serve as another way to document the expected behavior of the code Briefly describe how this PR is tested, and point to the specific tests you added. For example: 'This new feature is covered by the `sqllogictest` cases added in `foo.slt`'. If this PR does not add tests, explain why. For example, if the change is already covered by existing tests, please mention it. You should also check the `codecov` bot reply on this PR to confirm the changed code is exercised. --> ## Are there any user-facing changes? No <!-- If there are user-facing changes then we may require documentation to be updated before approving the PR. If there are any breaking changes to public APIs, please add the `api change` label. -->
Dandandan
approved these changes
Sep 28, 2026
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Which issue does this PR close?
Rationale for this change
apache#22298 updated the logical plan optimizer to apply optimization rules in place to avoid
Arcunwrap/rewraps with a newmap_children_mut()function. This function unconditionally updates the children of all logical plan nodes except forLogicalPlan::Extensionnodes. ForExtensionnodes, it only updates the children if the mapping function returnstruefor any of the children, signifying that a child was updated.When the
EliminateLimitrule prunes a limit that has 0 skip and fetch, it modifies the node but does not return that it modified anything. This is fine for every case except for if the limit is underneath aLogicalPlan::Extensionnode, since it that case we ignore the output from the rule.What changes are included in this PR?
This change adds a failing test, a fix to
EliminateLimit, and changesmap_children_mut()to unconditionally update the children ofLogicalPlan::Extensionnodes. The change tomap_children_mut()could be left out, but I wouldn't be surprised if there are other optimization rules that modify the node without returningtransformed=true, so this is done to avoid finding and fixing all of those cases.What is the testing strategy for this PR?
I added a test that replicates the issue and fails without my fixes.
Are there any user-facing changes?
No